Numerical Study on the Radiation Characteristics of Hydrogen-Blended Natural Gas Combustion

Thermal radiation is one of the main heat transfer mechanisms in boilers. This work numerically investigates the impact of hydrogen-blended natural gas combustion on the radiative heat transfer characteristics of the flame flue gas, to reveal the influence of hydrogen on natural gas combustion and heat transfer. To address the lack of study on radiative heat transfer and applications of accurate radiation models in simulating hydrogen-blended natural gas combustion, this work is conducted based on the newly developed weighted sum of gray gases model (WSGG) for hydrogen-blended natural gas combustion. The multi-physics coupling effect of fuel hydrogen content on radiative heat transfer, temperature distribution, and chemical kinetics are discussed. By constructing a numerical simulation framework, the numerical simulation method was first validated through a thermal companion burner, and then applies it to a numerical study of a 40 kW-class furnace, the influence of 0 ~ 75% hydrogen blending on the radiative heat transfer was systematically analyzed. The results indicate that as the hydrogen blending ratio increases from 0% to 75%, the peak flame temperature rises from 2180.5 K to 2291.8 K, the outlet flame temperature decreases from 864 K to 815 K, and the overall gas effective average absorption coefficient increases, resulting in a radiation ratio increase from 27.22% to 29.42%. The summarization of these qualitative rules and quantitative results has important reference value for the application of hydrogen energy and the optimization of boiler efficiency.